The present invention relates to a novel process for preparing amidosilanes and amidosiloxanes. More particularly, the present invention relates to a process for preparing amidosilanes and amidosiloxanes comprising reacting an organic amide and an Si--H containing compound in the presence of a precious metal containing catalyst.
Precious metal containing hydrosilation catalysts, especially those based on platinum, are well known in the art, for example, as described in U.S. Pat. Nos. 2,823,218; 3,159,601; 3,159,662; 3,220,972; 3,419,593; 3,516,946; 3,814,730; all of which are incorporated by reference into the present disclosure. Generally, these patents teach the addition of an organosilicon material having a hydrogen atom bonded to silicon to an aliphatically unsaturated material having either olefinic or acetylenic unsaturation resulting in the formation of an adduct having a new silicon-carbon linkage. Such reaction can be illustrated with respect to the olefinic bond as follows: ##STR1## These references, however, do not teach or suggest that the disclosed catalysts are effective for promoting substitution reactions of the type contemplated by the present invention.
de Benneville et al., U.S. Pat. No. 2,876,209, discloses that silicon-containing organic compounds can be prepared by reacting at a temperature of from 10.degree. C. to 180.degree. C., (1) an organic compound consisting of carbon, hydrogen, and at least one atom attached directly to a carbon atom selected from the group consisting of oxygen, sulfur and nitrogen, said compound containing at least one reactive hydrogen atom attached directly to an atom selected from the group consisting of oxygen, sulfur and nitrogen atoms, and (2) a silicon-containing compound having the formula ##STR2## where R is a lower alkyl radical, R.sup.1 and R.sup.2 are selected from the group consisting of radicals directly attached only to the adjoining nitrogen atom and radicals which together and with the adjoining nitrogen atom form a heterocyclic nucleus, and y is a number of from 1 to about 9. This reaction has the advantage that no catalyst is required, however, it also has the disadvantage that an amine is liberated as a by-product.
Hurwitz et al., U.S. Pat. No. 2,876,234, teaches that aminosilanes of the general formula EQU (R.sup.0).sub.4-x Si (N R.sup.1 R.sup.2).sub.x
where R.sup.0 is cyclohexyl, aryl, alkenyl or alkyl; R.sup.1 and R.sup.2 together may be the morpholino residue, the piperidino residue or the pyrollidino residue, or separately, R.sup.1 may be cyclohexyl, phenyl, aralkyl or alkyl, R.sup.2 may be hydrogen, cyclohexyl, aralkyl or alkyl, and x is an integer from 1 to 4; can be reacted with an amide containing a reactive hydrogen to obtain an amidosilane. This process, however, suffers from the disadvantage that large quantities of amine salts are produced as a by-product.
Golitz et al., U.S. Pat. No. 3,417,047, discloses that N-silyl substituted carboxylic acid amides can be obtained by reacting a halosilane or halosiloxane with a carboxylic acid amide in the presence of an acid-binding agent such as pyridine or trialkyl amine. Again a salt by-product is produced which must be disposed.
Klebe, U.S. Pat. No. 3,488,371, assigned to the same assignee as the present invention, describes linear difunctional silylamides which can be produced by reaction of dihalosilicon compounds with an organic amide in the presence of specific tertiary amines.
Toporcer et al., U.S. Pat. No. 3,776,933, teaches the preparation of amidosilanes by mixing a sodium salt of an amide with a chlorosilane in an inert organic solvent, filtering the by-product sodium chloride, and thereafter removing the organic solvent by distillation to obtain the product amidosilane.
Mitchell et al., U.S. Pat. No. 4,252,977, assigned to the same assignee as the present invention, provide a process for forming an acetamide compound of the formula ##STR3## where R, R.sup.1, R.sup.2 and R.sup.4 are monovalent hydrocarbon radicals and R.sup.3 is a divalent hydrocarbon radical, comprising
(1) reacting a silane of the formula ##STR4## where R is as previously defined and X is a halogen with a compound of the formula ##STR5## in the presence of a platinum catalyst, where R.sup.22 is a divalent hydrocarbon radical and R.sup.4 is as previously defined, to form an intermediate, and PA0 (2) reacting the intermediate with an amide of the formula ##STR6## to produce the desired product. PA0 (a) an Si--H containing compound and PA0 (b) an organic amide in the presence of PA0 (c) a precious metal containing catalyst. PA0 (a) an Si--H containing compound and PA0 (b) an organic amide in the presence of PA0 (c) a precious metal containing catalyst.
Each of the foregoing references suffer from a disadvantage such as salt or base (e.g. amine) by-product is formed. It has now been discovered that amidosilanes and amidosiloxanes can be prepared by reacting an organic amide having an active hydrogen atom with an Si--H containing compound in the presence of a precious metal containing catalyst, yielding hydrogen gas as the reaction by-product.